1. Field of the Invention
This invention relates to the preparation of natural tissue for implantation.
2. Description of Prior Art
In the past, natural tissues in the form of heart valves, arteries, veins and the like have been prepared for implantation by subjection to a bath of tanning fluid, but have possessed serious shortcomings upon completion of the tanning process. Shape retention, strength and life of the tissues upon implantation are among the areas of deficiency for such prepared tissues.
A major improvement was effected by subjecting the tissue structure to tanning fluid under pressure to cause it to assume substantially its natural configuration during the tanning period. Such a process is described in patent application Ser. No. 324,217 for Arrangement for Preparing Natural Tissue for Implantation, filed Jan. 16, 1973, by Warren D. Hancock and Frederick P. Sattler, now abandoned, and its continuation-in-part Ser. No. 490,686, filed July 22, 1974. This resulted in improved architecture of the tissues, higher tensile strength and greater and more uniform penetration of the fixative. However, the tissues treated in this manner nevertheless were considerably more rigid than corresponding tissues in their natural state. The lack of flexibility may prevent such tissues from achieving maximum life and performance upon implantation.